Proteins and especially immunoglobulins play an important role in today's medical portfolio. Expression systems for the production of recombinant polypeptides are well-known in the state of the art and are described by, e.g., Marino, M. H., Biopharm. 2 (1989) 18-33; Goeddel, D. V., et al., Methods Enzymol. 185 (1990) 3-7; Wurm, F., and Bernard, A., Curr. Opin. Biotechnol. 10 (1999) 156-159. Polypeptides for use in pharmaceutical applications are mainly produced in mammalian cells such as CHO cells, NSO cells, Sp2/0 cells, COS cells, HEK cells, BHK cells, PER.C6® cells, and the like.
For human application every pharmaceutical substance has to meet distinct criteria. To ensure the safety of biopharmaceutical agents to humans, for example, nucleic acids, viruses, and host cell proteins, which would cause severe harm, have to be removed. To meet the regulatory specification one or more purification steps have to follow the manufacturing process. Among other, purity, throughput, and yield play an important role in determining an appropriate purification process.
Due to their chemical and physical properties, such as molecular weight and domain architecture including secondary modifications, the downstream processing of immunoglobulins is very complicated. For example, are not only for formulated drugs but also for intermediates in downstream processing (DSP) concentrated solutions required to achieve low volumes for economic handling and application storage. Furthermore short concentration times are favored to ensure smooth processes and short operating times. In this context imperfect TFF processes especially after final purification steps can cause sustained damage even affecting drug product. The correlation between shear stress and aggregation in tangential flow concentration processes for monoclonal antibody (mAb) intermediate solutions was investigated by Ahrer, K., et al. (J. Membr. Sci. 274 (2006) 108-115). The influence of concentration time and selected flow and pressure on process performance and aggregation status was monitored (see e.g. Dosmar, M., et al., Bioprocess Int. 3 (2005) 40-50; Luo, R., et al., Bioprocess Int. 4 (2006) 44-46).
Mahler, H.-C., et al. (Eur. J. Pharmaceut. Biopharmaceut. 59 (2005) 407-417) reported the induction and analysis of aggregates in a liquid IgG1-antibody formulation formed by different agitation stress methods. In U.S. Pat. No. 6,252,055 a concentrated monoclonal antibody preparation is reported. A method for producing a concentrated antibody preparation is reported in US 2006/0182740. A combined process including an ultrafiltration, a diafiltration, and a second ultrafiltration sequence is reported in US 2006/0051347. In EP 0 907 378 is reported a process for concentrating an antibody preparation using a cross-flow ultrafiltration with a fixed recirculation rate of 250 ml/min. Methods for tangential flow filtration and an apparatus therefore is reported in US 2004/0167320. In WO 97/45140 a concentrated antibody solution is reported.